Fluid mining of underground ore deposits



Dec. 25, 1962 J. N. PEW m FLUID MINING OF UNDERGROUND ORE DEPOSITS FiledSept. 2, 1960 Fluid'+ Ore "To Separator INVENTOR. JOSEPH N. PEW,]I[ "m(a ATTORNEY Patented Dec. 25, 1962 3,070,361 FLUID MINING F UNDERGROUND()RE DEPOSITS Joseph N. Pew Ill, Gladwyne, Pa., assignor to GeneralCrude Oil Company, Houston, Tex., a corporation of Delaware Filed Sept.2, 1960, Ser. No. 53,678 7 Claims. (Cl. 262-1) This invention relates tothe mining of underground ore deposits by erosion thereof with fluidsand more particularly by injecting air and Water through a pipeextending into the deposit and carrying means adapted to loosen oreparticles from the deposit wall.

Mining of ore deposits, such as phosphate rock, conventionally is doneby loosening the deposits by mechanical means or explosives andtransporting the ore particles in dry form from the mine. In cases wherethe deposits are relatively shallow, e.g. 50200 feet beneath thesurface, strip mining is often practiced by removing the overburden toprovide access to the ore. The removal of many tons of earth overlyingthe deposit, however, is a costly rocedure. Proposals have been madeheretofore to utilize erosion of the deposit by water as a means ofmining but none of these appears to have been successful except in caseswhere the deposit is composed of water soluble material such as rocksalt.

The present invention provides an eifective method for fluid mining ofore deposits which are not water soluble. The process is particularlyuseful in the mining of phosphate rock. The invention also embraces thecombination of apparatus for practicing the process.

According to the invention a borehole is drilled from the ground surfaceinto the ore deposit and a casing is set in the hole with its lower endterminating at an upper part of the deposit. A fluid inlet pipe ofsmaller diameter is positioned within the casing to form therewith anannulus which serves as a fluid outlet. A tough flexible hose isattached to the bottom of the pipe preferably through a swivel joint.The hose is of suflicient length that at least a substantial part 'of itcan contact the deposit wall during operation of the process. Water andair are pumped down the pipe and a high rate of fluid flow is maintainedsuch that passage of the fluids from the hose causes the hose to move orflap vigorously, thus beating against the deposit wall. The blast ofwater and air against the deposit together with this beating action ofthe hose readily loosens the deposits. The loosened particles aresuspended in the fluid and carried up the annulus and out of the casingwith it. The mixture is then sent to suitable separating means forremoving the ore particles from the water. If desired, the separatedwater can be recycled in the process.

Another feature of the invention involves the use of a plurality ofcleats or lugs made of hard material such as steel and attached insuitable fashion to the flexible hcse. As the hose beats against thedeposit, the cleats cut into the ore and increase the rate at which itis loosened.

Still another feature of the invention involves the introduction intothe hole in the deposit of pieces of a hard solid material preferablyhaving sharp edges. The material is selected with respect to particlesize and density such that movement of the fluid in the hole causescontact between the particles and the deposit wall but the particles arenot transported by the fluid up the casing annulus. The contact betweenthe particles and the deposit further enhances the rate of erosion. Forthis purpose small chunks of metal, hard rock or the like, can be used.By way of illustration but not in limitation of this feature of theinvention, steel blocks having dimensions of one-quarter to three inchescan be employed. The appropriate dimensions of the abrading chunks willdepend upon the density of the material and the velocity of the fluidspassing through the hole.

The invention is more specifically illustrated in the accompanyingdrawing which diagrammatically shows a borehole extending to a bed ofore and the arrangement of apparatus used in practicing the invention.

Referring to the drawing, numeral 10 represents the ground level and 11is a casing positioned in a borehole which has been drilled into the bedof ore. A pipe 12 centered within the casing is secured to a flange 13which closes the annulus at the top of the casing. Pipe 12 is connectedto water line indicated schematically at 14 and provided with water pump15 and also to air line 16 having blower 17. A fluid outlet line 23leads from casing 11 to a separator (not shown) adapted to remove theore from the water.

The lower end of pipe 12 preferably is provided with a swivel joint 18to which is attached a tough flexible hose 19 constructed, for example,from neoprene rubber. Hose 19 is of such a length that a substantialpart of it can abut against the wall 20 of the deposit. The hosepreferably is provided with a plurality of cleats 21 carried by metalbands 22 secured to the hose.

In conducting the mining operation, water and air are pumped at highrates through line 12. Exit of the fluid from the end of hose 19 causesit to flap vigorously against the deposit wall 20. impingement of thefluid mixture on the wall together with this flapping action loosens thedeposit, and the ore particles are carried by the fluid mixture up thecasing annulus and out through pipe 23. From time to time as the hole inthe ore bed gets larger, pipe 12 can be removed from the hole and hose19 can be replaced by a longer hose so that effective mining of the orecan be continued.

I claim:

1. Apparatus for mining an underground ore deposit comprising, incombination, a casing extending from ground level to the deposit, afluid inlet pipe positioned Within the casing and forming an annulustherewith, closure means for the annulus at the top of the casing, atough flexible hose positioned within the deposit and connected to thebottom of said pipe, said hose having a flexibility and length such thatit is capable of flapping against the wall of said deposit, means forintroducing air and water into said pipe at rates such that the flow ofthe mixture thereof out of said hose effects vigorous movement of thehose in contact with the deposit and means for withdrawing fluidcarrying loosened ore particles from the upper part of said annulus.

2. Apparatus according to claim 1 also including a plurality of cleatsattached to said hose to aid the loosening of the ore from the deposit.

3. Apparatus according to claim 2 also including a swivel joint betweenthe bottom of the pipe and the flexible hose.

4. Apparatus according to claim 1 also including a swivel joint betweenthe bottom of the pipe and the flexible hose.

5. Method of mining ore from an underground deposit which comprisesdrilling a borehole extending into the deposit, positioning a casing inthe borehole with its lower end terminating in an upper part of thedeposit and a pipe within the casing forming an annulus therewith andattached at its lower end to a tough flexible hose positioned in anuncased portion of the hole, said hose having a flexibility and lengthsuch that it is capable of flapping against the wall of said deposit,pumping air and water downwardly through the pipe at a rate such thatthe passage of the fluids from the hose effects vigorous movementthereof against the wall of the deposit, whereby particles of ore areloosened from the deposit, and withdrawing fluid carrying loosened oreparticles from the upper part of said annulus.

6. Method according to claim 5 also comprising intro- 5 ducing into thehole in the deposit a relatively hard parparticulate solid materialhaving a particle size and density such that movement of the fluidcauses contact between the particles and the deposit Wall withouttransport of the particles up the annulus, whereby erosion of the 10deposit is enhanced.

7. Method according to claim 5 wherein the ore deposit is phosphaterock.

References Cited in the file of this patent UNITED STATES PATENTSSchweitzer et a1 Oct. 22, 1935 'Brinton Feb, 4, 1958

